We will continue study on: 1. The lac repressor-operator interaction. 2. The molecular mechanism of action of bromodeoxyuridine (BrdU), a drug that selectively blocks the expression of differentiated functions in mammalian cells. 3. The molecular mechanism of X chromosome inactivation in mammals. 4. Eukaryotic chromosome isolation, separation, and characterization. 5. The biological function of DNA methylation, with the aim of proving the involvement of DNA methylation in gene regulation and X inactivation.